The National Transportation Safety Board (NTSB) says they are investigating multiple factors as they look for a cause of a fatal crash between a commercial airplane and a military helicopter in Washington DC
A preliminary report will be issued in 30 days, with NTSB officials saying they "have a lot of information but... need some time to verify that"
No flight data recorders, also known as black boxes, have yet been recovered from the scene, investigators said
President Donald Trump earlier offered his condolences, saying "our hearts are shattered" by the incident on Wednesday night
No one is believed to have survived, officials say - 64 people were on the American Airlines flight and three on the helicopter
Trump blamed diversity rules under his predecessors, saying he believes people hired for air traffic control roles were not always qualified - but offered no evidence for this
In an audio clip, air traffic controllers can be heard asking the helicopter's crew if they can see the plane
US Defence Secretary Pete Hegseth said "a mistake was made" and it appeared to be some sort of elevation issue
BBC Verify analyses moments before Washington DC plane crash
Wichita Mayor Lily Wu is now taking questions and the first reporter asks whether or not they know how many of the passengers were Wichita residents.
Wu says they don't have that information nor the passenger manifest yet.
Wu stresses that any information for families and friends should be directed to American Airlines - and repeats that you can get that information at the helpline the company set up (1-800-679-8215).
Wichita City Council and multiple faith leaders in the city will be coming together for a community wide prayer at 12:00 local time (18:00 GMT), the mayor notes.
"At this time our community needs to come together to support the family members that have been impacted," she says, noting that additional resources have been made available for city council staff who have been impacted.
Image source, City of WichitaCongressman Ron Estes says he has spoken to the White House about the "tragic" incident.
Wichita is a close-knit community and the incident will have consequences for years to come, he says.
He adds that the investigation will take days and weeks, but that they hope it will prevent such accidents in the future.
Image source, City of WichitaWichita Mayor Lily Wu is up at the podium, with a few officials alongside her.
She says that the city's hearts are heavy, and that they are still learning details about the tragedy.
She thanks the first responders who have been working through the night and becomes tearful when she confirms that her teams have been told there are no survivors.
This is a terrible tragedy that will unite the city, Wu says, adding that families of victims will be informed before their identities are released.
Shortly after reporters were addressed by officials in Washington DC, we're now hearing from Wichita authorities.
The American Airlines flight that crashed took off from Wichita, Kansas.
You can follow along by pressing watch live at the top of the page and we'll also bring you the key news lines here.
By Jake Horton, BBC Verify
We have verified two pieces of audio from the control tower overseeing air traffic at Ronald Reagan Washington National Airport.
The timing of the audio - uploaded to a website which logs air traffic control communications - matches the timing of the collision at about 01:48 GMT (20:48 ET local time).
In one clip you hear what appears to be an air traffic controller say: “PAT 2-5 [helicopter] CRJ [passenger aircraft] in sight… PAT 2-5 responding CRJ.”
This is followed by what appears to be the helicopter pilot saying: “The aircraft is in sight, requesting visual separation.”
About 15 second later in the clip you can hear what appears to be someone in the background say “ooh”.
In a separate recording from the control tower, you can hear additional dialogue in the moments before the crash. What appears to be a flight controller says: “PAT 2-5 CRJ in sight… PAT 2-5 pass behind CRJ.”
Shortly after you hear an “ooh” – as in the first clip – and then about 12 seconds later someone says: “Tower did you see that?"
We've more now from the scene of the accident last night.
In an audio recording, air traffic controllers can be heard telling the military helicopter to avoid the commercial flight carrying 60 passengers.
As you can hear below, the control team then begins diverting flights nearby after appearing to see the helicopter and plane collide.
Air traffic controllers appear to try to stop collision
We heard a little earlier from local officials in Washington DC after the US suffered its first major commercial air crash in nearly 16 years.
Here's the latest information you need to know:
Image source, Reuters
Bernd Debusmann Jr
Reporting from Alexandria, Virginia
I'm currently in Alexandria, Virginia - just south of the airport down the Potomac River.
On a normal day, this would be a quiet place. This morning, however, is loud. Helicopters have been flying back and forth along this stretch of river, and several police patrol points are bobbing nearby.
In the distance, I can see at least a dozen sets of red and blue police lights flickering closer to the sight of the crash.
Jonathan Josephs
BBC business reporter
It’s likely this crash will renew questions about safety in the US aviation industry.
Last year the US government approved 10 new flight slots for Reagan National Airport despite opposition from some local politicians over congestion concerns after some near misses.
Reports of the conversations between air traffic controllers and the aircraft suggest that the controllers were alert to the dangers as this accident was unfolding.
Nonetheless there has been a shortage of air traffic controllers in the US in recent years and last year Congress authorised the regulator, the FAA, to recruit more.
That comes after the FAA said it hired the most in nearly a decade last year to address a shortage of around 3,000 personnel.
It’s an issue that the boss of United Airlines, Scott Kirby, told NPR last month was “the biggest opportunity to make air travel better for customers in the United States” by reducing delays.
Image source, Getty ImagesAfter fielding questions from the press, DC Mayor Muriel Bowser brings the press conference at Washington National Airport to a close.
We're expecting to hear another statement to the press from authorities in Wichita, Kansas - where the commercial flight departed from - at 08:00 local time; that's in about 45 minutes.
We'll bring you updates when we have them, but in the meantime, stick with us and we'll bring you some analysis on what we've just heard.
The transport secretary then answers questions about the pilots, saying both were experienced.
The helicopter's mission was classed as a "training mission", which he says could lead people to think someone inexperienced is in the cockpit, but he says not to "read into that".
Duffy also says he will wait for all the information to come through but he thinks the incident was preventable.
He also confirms that President Donald Trump will be in the Situation Room this morning and has been kept in "full appraisal" of what's taking place.
Secretary of Transport Sean Duffy is now answering questions about the flight path of the helicopter and air traffic control at the time of the incident.
He says he doesn't want to go into too much detail about the information from the Federal Aviation Administration but that prior to the collision, the flight paths of both aircraft were not unusual for DC airspace.
As this investigation moves forward we'll provide more information, he says.
On air traffic control he also says he won't make a statement but adds that everything was standard in the lead up to the crash.
"Obviously something happened," he says, adding that we will learn more as the investigation progresses.
Duffy is also asked about communication between the helicopter, the commercial plane and flight control - he says there was no breakdown in communication between the military helicopter and the American Airline flight.
"The helicopter was aware that there was a plane in the area," he says.
DC Fire and EMS Chief John Donnelly answers the next question, about the size of the debris field.
He says that the wind has caused debris to travel from the airport as far as the Wilson Bridge, which he says is less than a mile away.
Answering another question on the next phase of the operation - which he confirms will be led by the National Transportation Safety Board - he says "all of us are working together to search the area and find all [the] victims."
"That will take us a little bit of time and we may need more equipment," he adds, specifically as it relates to collecting the debris from the crash.
DC Mayor Muriel Bowser takes the first question from the media, with a reporter asking if the DC official can say if it's safe to fly.
Bowser says that what she can talk about today is the specific crash and that the National Transportation Safety Board is going to continue to investigate the situation.
She adds that she doesn't believe anyone of us has been briefed on anything that would suggest any other aircraft is implicated.
Metropolitan Washington Airport Authority president Jack Potter also stresses that the airport is safe to reopen at 11:00 and that the runway is operating away from the ongoing recovery operations.
He adds that airlines will communicate with their passengers about their travel.
Image source, ReutersWe're hearing from a couple of senators now, one of whom is Senator Tim Kaine.
He says that there will be a lot of questions, which is the National Transportation Safety Board's, (NTSB) job to investigate.
It's not a time to speculate, but a time to investigate Kaine says, before adding that he is confident this will be done.
Metropolitan Washington Airport Authority president Jack Potter says the Ronald Reagan National Airport will open at 11:00 local time (16:00 GMT) today.
Image source, ReutersAmerican Airlines CEO Robert Isom is now addressing the crowd gathered at the airport.
"This is devastating" Isom says, extending his condolences to everyone involved.
"Our focus right now is to do everything we can to support everyone involved," he adds, saying that families and friends looking for information about their loved ones can call the helpline (1-800-679-8125) that's been set up.
Isom explains again the details of the crash and reiterates that the American Airlines flight descended "in normal approach" to Reagan National Airport.
At this time we don't know why it collided with the helicopter, Isom says.
He again confirms that there were 64 people travelling on board the flight - four crew members and 60 passengers.
Donnelly continues as he names and thanks the agencies involved in the search and rescue operation for their work.
However, he says that despite these groups' efforts, they are now switching from a rescue operation to a recovery operation.
"We don't believe there are any survivors from this accident," he says.
He adds that his teams have recovered 27 bodies from the plane, and one from the helicopter.
Image source, ReutersDC Fire and EMS Chief John Donnelly is up next and says that last night at 20:48 local time (01:48 GMT) the control tower sounded an alert which alerts responders to a report of an aircraft crash.
He says that set off an immediate response.
Donnelly says that very quickly this call escalated and responders realised the extent of the crash and responded with 300 people.
These responders found frigid conditions, heavy wind, ice on the water and operated all night, he says.